A power recovery type refrigeration cycle apparatus in which the energy of expansion of refrigerant is recovered by an expander and the recovered energy is utilized as a part of the work of a compressor has been proposed. For example, a two-stage rotary expander such as disclosed in JP 2005-106046A has been studied as an expander used for such a refrigeration cycle apparatus.
FIGS. 10A and 10B are horizontal cross-sectional views of a conventional two-stage rotary expander 200. FIG. 10A shows a first stage cylinder 205 (first cylinder 205) and FIG. 10B shows a second stage cylinder 206 (second cylinder 206). The refrigerant drawn into the first cylinder 205 expands in an expansion chamber, which is constituted by a working chamber 215b of the first cylinder 205, a working chamber 216a of the second cylinder 206, and a communication hole 204a for allowing communication between the two working chambers 215b and 216a. The first cylinder 205 and the second cylinder 206 are partitioned vertically by an intermediate plate, and the communication hole 204a is formed so as to penetrate through this intermediate plate across its thickness direction. Employing such a construction makes it possible to partition the working chamber 215a for drawing refrigerant, the working chambers 215b and 216a for expanding the refrigerant, and the working chamber 216b for discharging the refrigerant easily. At the same time, it allows the suction-side working chamber 215a to perform 360° continuous suction, making it possible to reduce suction pulsing.